INSECTS : THEIR MOUTHS. 140 



clrical joints, which are beset on all sides with short 

 arched hairs, but have besides a whorl of radiating long 

 hairs surrounding the bottom of each joint. The effect 

 of this is exceedingly light and elegant. 



Between these projects a long cylinder, which repre- 

 sents the lower lip (labium) ; it slightly swells towards 

 the tip, where it forms a round, nut-like knob, covered 

 with exceedingly minute papilla 1 , and no doubt consti- 

 tuting a highly sensitive organ of touch. For the greatest 

 part of its length it is covered with lined scales, and with 

 short arched hairs like the antennae, while each side of 

 its base is guarded by a labial palp of three joints. 



On applying a graduated pressure, slowly increased to 

 actual contact of the plates (or as near an approximation 

 to it as we can effect), we see first that the nut-like tip 

 of the labium expands into two concave leaves, like the 

 bracts of a bud, and displays two pairs of more delicate 

 leaves within them. Then, from a groove along the upper 

 side of the labium spring out several filaments, of great 

 elasticity, and of the most delicate tenuity. One pair of 

 these represent the mandibles ; they consist each of a 

 very narrow blade, with a stronger back like that of a 

 scythe. Their tip is brought to a most acute point, and 

 the edge in immediate proximity to this is cut into about 

 nine teeth, pointing backward ; the rest of the edge is 

 smooth, but the whole blade is crossed by a multitude of 

 oblique lines of great delicacy, which may be intended 

 to keep the edge constantly keen. 



Next come the maxillce, or lower jaws, horny filaments 

 as long as the former, but still more delicate, constituting 

 simple cutting lancets, with a back and a keen blade, a 

 little widening at the tip. 



Besides these there is the tongue, consisting of a cen- 

 tral rod which is distinctly tubular, and of a thin blade 

 on each side, fine-edged and drawn to an acute point. 

 And also the labrum or upper lip, an organ having the 



